Pyrometer.



E. L. CLARK.

PYROMETER.

APPLSCATIDN FILED DEC. 19. 1912.

1,305,325, I Patented Nov. 21, 19%? WETNESSES I iRVENTOR v EBQEFKSON L..CL-ARK.

ATTORNEY gunctwns 2 EIEEESGL' L. SL233, $5 LALWOQD, D7510, .ASSIGNGR T ZIATIOIQAL CARES CGEAIPAE GE CLEVELAND, OHIO, A COIRPQBATIG'N OF KEV!" JERSEY.

EYE GME Specificacicn of Letters Pa'ken z.

Application filed. December 19, 1312. Serial 22's. 73?,53G.

To aZZ whom i6 1m. cancer-1a.

Be 1t knc'wn thai, Enmnsa L. CLARK,

:1 citizen of the Unitci Stat-es, residing at akewood, in the county of Cuyahoga' and State of Dixie, have invented a certain new and useful Emprcvement in Pyrometcrs, 01 which the 'EOHm-ving is 3 E1111, clear, and exact descrlpt-icn.

My im'cnti-on relates to pyramcter s tems and prcvidcs means for correcting in.-

.accuracies due is change in temperature. of

cold junctions in the thermopile.

In thcrmopiies the cold junctions generate'E. F33 but in a direction opposed to thc E. M. cf hot. junction. .Th E. i iuprassad on the gzzh'anomete ls tillefsre n that 01'' the hot junction. Consequen a -c 'ancc must be made for which the compc'nsai-icn is pparcnf. from the fol.-

reference being had in) Figure 1*1' a sai-ing system. iliustz'ates the cir Fi of a compensating; system. Fig. =72 is a i mgrmmna ic a -mngcmcnt of the uircu. the system 3110 in ?.-l'3'f61"i1lg in l, the thcznucpiic ijliiIStl'fli-ih has 310i 'jui i and c016. d 3. Thc'coid. jimct-iou is Calumet-cc xiireciuflic terminal 4: of a ncmcicz' he juncticii 2 is connect-e6. tmcl 1. rcsistmicc. 1" and 9. source of E. F. 5 a. paint compensating coil 9' has one ierminnl cczmcctcrl m the ca 1 juncme to the point- 8. in two branches, source of E. M. F. the othcl 10. The

610B 2- and the ofl Here the circuitcnc carts-riding throw. 9,-1'esistcnce 7* i0 21 through resiatance 1* point 10 is confine...

iimt mania aim: be imvinn' the gab-mom -r. The compensating 00721 is Wound arcimd, Gl othcrwisc arranged in 01056 proximity to the co jemction so that it \vlii be szflqect-cd to the same tam- ...m 1 geWcLe. .z 1es1s.-am.e,. oi mums. would be 210138211, insulated that no contacts 'i I yrqmc be. made an ether 510111t3-than UhOSB suits are shcwi 4 -11 Fig. 2. The sour i E. M. F. {1 9 may be one or more 14 09113, for Hovevcr, any m'zhsz source bf F. that has 9.- substaniiailg' ccnstant gs may be uscti. The across 6 and 9 connected. shown wit a positive jnined to. her. file til...

l mill is canwords smile as, e. fiowir and v x'csistwltfcs 2' and inn! wrntnr s 0f the: void junctions redegrees and the. -.rature pallet-ion be misc-G. some 42m: degrees. the w I. F. gem

.119. hot junction would =e-url c112- ,"Qili; through resistance W, batten 6, rcsis"s.

:mcc rinc i til-c guh'anonieter G. The 2211- auzomct'ei' wculci be so calibracfi tim iit .muid indicate the wit-age. 52E temperature at the 510i jmuziicn 1 with the 1 "chances z1rran- 1 as shown. If. ho'i'chr. the acid. 1mm. moms also increase an temperature $115,

rcsuitant witugc' prcduced by the then mopiifi would be i'eiiuccd due $5 3 in the bucking T l. M. 0f the cold juncbions. Thu increase tempcmturc c f-thc cold junctions, "newever, incrgass illeresistznore diagram- I #:cd to the negative terminal 01 the rconce '2" sinceil; has e. positivetemperature coefiicicnt of r'csietancel This increase in resistance of Coil 1" cuts clown the current drained from battery 6. The decrease of 5 current decreases the drop in the line resist once 7 and therefore raises the voltage hetwecn the points '7 and The voltage between the points l and hes not been changed since the coils have not changed in resistance. Then by usinglu. resistance 9" of suitable value and of suitable POSitiVB tennpe'ature coei'licient, this rise in voltage between points 7 and 8 may he mndc to substantially equal the decrease in voltage of the thermocouple clue to increased eohl junction temperature The voltage around "the circuit'v battery 6, '1'. gul'mnometer G and the thermocouple therefore remains the same. The reading will therefore be the same regardlcss'of the increase of temperature in the colcl junctionsv If the cold junction temperature drops below 2% degrees and the hot junction remains at 900 degrees the resultant E. M. F. of'thc thermocouple would. be increased and if there were no compensating arrangement the galvanometc-r would indicate a. greater voltage or temperature than. actually existed at the hot junction. However, with the compensating system shown a. decrease in our peruture at the cold junctions al' 1 means a decrease 01" resistance of the coil r. This decrease in the reeistance causes an increase in the current (ire-Wu from the battery 6 which may be traced through point 8, re

sistance 3/, point 7 hack to the battery 6.

The increase of current through resistance r increases the drop therein and hence 1c creases the voltage applied to the coil 7- Thus the potent- .1 between the points 8 anti 7 has been diminished. This (icr ease of potcntial equals the illtlmifil. in voltage of the thermocouple, so that the ;=ltng'c nrouncl the circuit r. battery 6, 1- gulmnometer (1- and thermocouple 1 remains the sumo. "l'he roiuling of the lvunouzeier will therutore he correct regardless of the deem-escin the ten'iperuture ol' the cohl junctions.

in at the circuits are arranged similarly to thoec in Fig. *2 with the except-ion of the location of the thermocouple. This is placed directly in... circuit hetwei-n'thc points 7 and- 8 with its positive terminal connected to the conductor lending to the point 8.

current flowing;

Suppose that the hot junctions and cold point 8 through resistance -r'- to point 10 mil lmck through reeistunru 1" to the buttery. it now the hot junction he ruisml to u lemperuturr, so) 900 llfigittffi. the l). M. l". of the thermocouple will he llIUl'UliHll. 'lhiinereusc of l'1.'.\l. l. wouhl ruisu the potential between the points 8 nnrl T. l'lupoints 1U illltll are tlu-relore at (liil'ereutpotentials and rurrenl. will flow from humor) (3 through point 5, resistance r. gulvumuueter (i. pniul T and resistance 1" luutlc to the halter-y. This will give the correct iiulirution on the gul'nc nometer of the temperature M the lml, junction of the tluu'zum-ouplv. ll now the eolil junction temperature rises while the hot junction temperature rrluuius at 1100 degrees the resultant .ll. M. l. of the tlleri'immuple is less than hel'ore. and their wouhl h.- u tendency for the gulruumuelvr to llHlll less than the true temmruturc of the hot junction. However, the iiut 'euse of temporalure at the eohl junction muses on iucrcusv in resistance of 2", which llllllllllh'll fb the through the shunt circuit contuiniug A .lulicu 1-" uml battery 0. The lrop in r [5 therefore (lo- 'iL'zlHlHl :uul the potential between the points 7 and is :mcorilingly increased. By choo1+ ing the proper values for the liSh'tilJlCUl-I the increase iu resistance in um he umrie to bring the (llll'ervmzv of potential Lctwceu the points 2 and #5 Luci: in what it was before the hwuuuu'uture ol the colil junctions inoreusvil HIH'l the ga 'nruuncter indication will he maintained correct.

if the tempiz-i'uture ol. the cohl junctions should drop below, any degrees. here-- unu lowers the ililicrcnre of po -nti;-. ivtweeu. the points 51ml H. 'llze rmt: e be I? tween these two poinls is therefore brought back to the some value as before the cold junction tcmperutmre decreased uncl'the reading of the gnlvnnonwter is brought bncl: to the correct value.

The resistances r 1*", 1*" and 'i' in ull the systems disclosed l'ierein would he made of metal that has t negligible temperature coellivient, many of which are to he: foun'i on the market. W'hen lhe systeme shown in i igs. 1 and Zhm-e been ln'oprrly arr: .1 re-(l the coluponsutiim is mr-rreet within a I action of fiper cent. for 11 wide of hot junction temperatures; and. therefore when the .itom is once at, no change of resist anees will be necessary.

l l l) The system shown in Fig. 3 has the advantage over that shown in Fig. 1 of requiring only two leads from the thermocouple to the ga-lvanometer system, While that in Fig. 2 requires three wires. This advantage, however, is-small as there is no serious objection to using three wires between the thermocouple and the galvanometer system. The system shown in Fig. 1 has the advantage over that shown in Fig. 3 in that the thermocouple circuit may be opened without throwing the high voltage of the batteries directly on the galvanometer.

Having described my invention what I claim is:

1. In a pyrometer system, a galvanometer, a thermocouple, a resistance having apositive teni erature coefiicient .located'closely adjacent" he cold junction of said thermocouple, ai -second resistance, said resistances being connected together at one end and being connected together at their other ends through the thermocouple and galvanome ter, and a source of E. M. F. in a circuit connected in parallel to each of said resistances.

2. In a pyrometer system, a galvanometer, a circuit connected thereto containing-a thermocouple and a resistance having a positive temperature coeflicient located closely adjacent the cold junction of said thermocouple, and a circuit in parallel to a part of said .first mentioned circuit containing a source of E. M. F.

In a pyroineter system, a galvanometer, a circuit connected thereto containing a thermocouple and a resistance having a positive temperature coe'lficient located closely adjacent the cold junction of said thermocouple,

and -a circuit in parallel to a part of, said first mentioned circuit containing a source of E; M. F. and aresistance. 4

4-. In a pyronieter system, a galvanomet-er, a circuit connected thereto containing a thermocouple and a resistance having a positive temperature coetiicient located closely adjacent. of the cold junction of said thermocoumosses ple, and a circuit in parallel to said resistance containing a source of E. M. F.

In a pyrometer system, a galranometer, a' thermocouple, a resistance having a positive temperature coefficient located closely adjacent the cold junction of said thermocouple, a second resistance, said resistances, galvanonieter and thermocouple being connected in series in a closed. circuit, and a circuit consisting of a source of M. and a resistance connected in parallel to the circuit containing each of said resistances 6. In a pyrometer system, a circuit con taining a galyanometer, a thermocouple and a resistance having a positive temperature coeflioient, said resistance being located adjacent-the cold junction of the thermocouple and a shunt circuitaround said resistance containing a source of E. M. F. and a second resistance.

7. In a pyrometer system, a galv'anometer, a thermocouple, a resistance of substantially constant value, a second resistance of posithe temperature coefiicient located closely adjacent the cold junction of said thermocouple, said resistances and thermocouple being connected in series to the terminals of said galvanometer, and a shunt circuit around said second resistance containing a source of E. M. F. and a third resistance.

8. In a pyrometer system, a galvanolneter, thermocouple, a resistance of substantially constant value, a second resistance of positivetemperature coefiicient located closely adjacent the cold junction of said thermocouple, said resistances and thcrmocouplebe- .ing connected in series to the terminals of said gelvanometcr, and a shunt circui around said first mentioned constant resistance containing a source of E. M. F. and a third resistance.

In testimony whereof, I hereunto affix my signature.

- EMERSON L. CLARK. lVitnesses i F. L. Wnrrn,

H. G. GROVE] 

